Recently, Internet-based solutions for multimedia communication have evolved and a large number of techniques have been proposed to enable acceptable quality video telephony over a best effort network, such as the Internet. As a result, a large number of Internet applications providing video-telephony services have emerged. Two well-known examples are Skype and Apple Computer's Facetime. Google and Facebook are also planning to provide video telephony services between their subscribers.
Advances in broadband mobile communication technology have also reached a point where mobile subscribers use their user devices, such as smartphones, tablets, and laptop computers, to access the Internet and perform tasks that recently required a computer with a fixed connection to the Internet. Due to the ubiquitous nature of mobile communications and the advances in broadband mobile communication technology, it is expected that large numbers of mobile subscribers will use user devices, such as smartphones, tablets, and laptop computers, for video telephony services.
The Internet is a best effort network and does not provide strict Quality of Experience (QoE) guarantees for an on-going video telephony session. This problem is more pronounced for users that access the Internet with user devices because of the potential change in the available rates due to factors such as the distance from the antenna, fading and network load. Another problem with video telephony over mobile access networks relates to handover between networks using different radio access technologies (RATs), which may provide different data rates and different levels of service.
The Third Generation Partnership Project (3GPP) has developed a Quality of Service (QoS) architecture that makes it possible to initiate and setup QoS-bearers. These QoS bearers can provide guaranteed latency, bandwidth, and/or data rates to mobile subscribers. While this mobile QoS architecture supports video telephony services over current mobile broadband networks, it is unlikely that current Internet video telephony applications will use this architecture. The main reason is that the capacity demand of a high-grade video service is high and that, due to radio resource limitations, providing video telephony service over a mobile access network would be very expensive for the service provider and/or mobile subscriber. The radio resource limitations will become more problematic with the appearance of high-resolution user devices and demand for high resolution video streams during video telephony sessions.
Therefore, a solution is needed for providing high quality video telephony services over mobile access networks.